Koi keeping is a fun hobby, however cleaning out of your mechanical and biological filters is often not done enough or correctly by koi keepers as it is not much fun to do.  Unfortunately it is part of having a koi pond and below I will discuss and give you guidelines on maintaining your mechanical filtration equipment. In part 2 we will discuss the maintance of the biological filtration. If you build your Koi pond with the correct filtration the maintance does not take as long as you may think, and once you have a routine in place it will become a quick job to do.
A common problem that does occur with some koi keepers is the misunderstanding that if you buy the correct filtration you will not have to clean any mechanical or biological filters.  Unfortunately this is incorrect but maintaining the filters is much quicker and easier to do.

Settlement chamber or discharge box:

The settlement chamber is designed to collect the solids before they get to the pump and then the biological filtration.  This box gets the dirt first and needs to be cleaned out and flushed went it is dirty.  When buying a settlement chamber make sure it has a outlet on the box that can run into a storm water drain or waste drain.
Filter brushes are good to use in this box, as they are easy to clean and can be shaken vigorously to get the dirt to fall off.  Depending on the amount of Koi fish you have and the fishes size will determine how often you need to clean out the settlement chamber.  Once a week should be sufficient but look at the settlement chamber to see if it needs to be cleaned more often.

Sand filters
Sand filters are best used after a settlement or discharge box to prevent them blocking up too quickly.  If your bottom drain is connected directly to the suction line of the pool pump you will have to back wash the sand filter more often. When buying a sand filter for a koi pond make sure you buy a Koi sand filter and not a swimming pool sand filter.  They are designed for koi ponds and work much more effectively.  You will be very unhappy if you have a normal swimming pool sand filter when doing maintance.  The biggest difference in maintance is that the koi sand filter has a clamp and a screw that keeps the lid on, making opening and closing the filter an easy job. The pool sand filter has 8 to 10 screws to hold the lid in place and undoing 8 to 10 screws 2 to 3 times when doing a hand back wash is not the quickest job.  The sand filter should be cleaned once a week and a hand backwash also needs to be done.  If you only place your sand filter onto backwash each week this is not good enough.  Backwashing your swimming pool like this is fine as chemicals are used to kill algae and microorganisms in the water, which therefore take up less space inside the sand filter. Koi ponds don’t use chemicals and the sand that is used in Koi sand filters is 3-5mm which is much larger than what you would use in a swimming pool filter.  The courser gravel is heavier and is not stirred that well by a normal backwash, therefore it is important to open it up and stir it manually by hand before doing a normal backwash. Doing a hand backwash also breaks a crust that tends to form on top of the sand filter.

By doing regular maintance on your koi pond you will see the benefit in your koi pond and the water clarity will be clean and clear.